Lubricant additive and lubricating compositions



United States Patent 0 3,261,781 LUBRICANT ADDITIVE AND LUBRICATING COMPQSITIONS Omar 0. Juveland, South Holland, 111., assignor to Standard Oil Company, Chicago, Ill., a corporation of Indiana No Drawing. Filed Nov. 15, 1963, Ser. No. 323,910 11 Claims. (Cl. 252 51.5)

where R is an alkyl group containing at least four carbon atoms. Compounds of this general type are useful as anti-rust agents in lubricant compositions; when reacted with alkyleneamine compounds, they are useful as detergent additives in motor oils, capable of dispersing various impurities and neutralizing acid products formed in motor oils during their use in internal combustion engines. I have found that particularly useful compositions for these purposes are those which are the telomerization reaction products of lower alkenes, e.g. ethylene, propylene, 1- butene and l-pentene, with 4-f-ormyl-phthalic anhydride and the ethylene-amine derivatives thereof, such as those made by reaction with tetraethylene pentamine.

Internal combustion engines employing leaded fuels, commonly gasoline containing tetramethyl and/ or tetraethyl lead, undergo blowby of combustion products past the pistons. As a result, various compounds of lead work their way past the piston rings to accumulate on many engine parts, such as the oil ring slots, oil lines, and the like. These lead-containing accumulations frequently obstruct the normal flow of lubricating oils used in the engines. Moreover, during the combustion of fuel in an internal combustion engine various oil oxidadation products, fuel soots and resins, and other type of insoluble matter are produced as a result of piston blowby of combustion products, high temperatures, sulfur compounds in fuels, etc. It is important that these materials be kept in suspension or dispersion in the oil so that they will not settle out or adhere to metal surfaces, whereby they build up as sludge or varnish deposits. The manner in which dispersant additives function is roughly analogous to the use of soap to bring some noncompatible material, such as soot, into a suspension with water, so that the soot does not settle out in lumpy masses. In like fashion, oxidation products, resins, soots, etc. will not mix readily with petroleum oils and will tend to settle out and adhere to engine surfaces. If a dispersant is added to the oil, these insoluble materials are dispersed or suspended so that settling and agglomeration into sludgy deposits is minimized. The dispersants act by adsorbing onto the foreign particles in such a Way as to increase the distance of closest approach of the particles and thus to decrease the effective inter-particle cohesive field of force.

Heretofore, aromatic hydrocarbons to which are attached long hydrocarbon substituent chains have been used as dispersants, and a variety of metallic additives have also been used in internal combustion engines to prevent tarnish formation and to disperse oil-soluble materials. These latter additives very often consist of such compounds as the alkali and alkaline earth salts of organic acids, such as sulfonates, phenates and phosphosulfurized hydrocarbons or mixtures thereof. Unfortunately, many of the metal-containing additives promote the oxidation of oil in an engine, so that their use is disadvantageous.

The increased use of passenger automobiles for high speed driving between major towns has led over the past decade to the development of larger and more powerful internal combustion engines for such vehicles. In practice, however, many of these vehicles are employed, for the major proportion of their lives, in city driving. The conditions an engine encounters in city driving are recognized to be much more severe than the conditions encountered in long distance, high speed driving. During the city driving the automobile engines develop only a small proportion of their maximum power output and as a consequence of the lower power output, these large engines work for long periods at temperatures lower than their full power working temperature. As a result, the alkali and alkaline earth salts of organic acids which hitherto functioned successfully as detergents and dispersants in crankcase lubricating compositions have been found to be less successful in dispersing the sludge formed under the low temperature operating conditions of city driving. Apparently, different types of dirt require different dispersants and the sludge formed under low tempe-rature operating conditions, termed cold sludge, has presented particular problems not encountered in the dispersing of high temperature sludge compositions. Further, acidic by-products of fuel combustion tend to accumulate in engine oil at a faster rate during city driving conditions wherein the oil does not become thoroughly warmed. A wide range of polypolar polymers have been disclosed as dispersants for the cold sludge. These polypolar polymers have usually been manufactured by copolymerizing monomers of relatively low polarity, particularly unsaturated esters such as esters of vinyl alcohol, with monomers of higher polarity.

I have found that surprisingly eflective compounds for use as cold sludge dispersant and acid neutralizing agents can be made from 4-alkanoyl-phthalic anhydrides. The 4-alkanoyl-phthalic anhydrides contain functional groups which can be reacted with other materials known to be value as extreme pressure lubricating agents, detergents, acid-neutralizers, etc. for the preparation of additive molecules capable of replacing several of the individual additives otherwise required in motor oils designed for severe service conditions. Further, the 4-alkanoyl-phthalic anhydrides themselves possess an anhydride function which is capable of adsorption onto the engine wall so as to provide rust inhibition.

The additive compositions of my invention can be added to lubricating oils in amounts as great .as 30 percent by weight and more. Generally, the total amount of additives in a lubricating oil for severe service does not exceed about 20 percent by weight, even in a high detergency oil. Smaller amounts of my additives can be used, depending upon the severity of the service encountered by the particular lubricating oil and desirably can be amounts of from about 0.01 percent by Weight to about 15 percent by weight and, preferably, from about 0.25 percent by weight to about 10 percent by weight of the lubricant base stock.

The average carbon chain length of the alkyl substituent in the 4-alkanoyl-phthalic anhydrides is selected according to the degree of solubility desirable for incorporating the 4-alkanoyl-phthalic anhydrides and the ethyleneamine derivatives of the 4-alkanoyl-phthalic anhydrides in a lubricant base stock. A very short alkyl substituent provides an additive with relatively low oil solubility, because of the desolubilizing influence of polar substituents in the total molecule; a very long alkyl substituent also provides an additive with relatively low solubility because of the decrease in solubility which accompanies an increase in molecular size; when the alkyl substituent is highly branched, it can in general contain more carbon atoms than a non-branched alkyl substituent at a given solubility level, since branched alkyl chains are more oil-soluble than unbranched alkyl chains. Alkyl substituents containing from 4 to 1000 carbon atoms are generally most useful in rust-inhibiting and dispersant additives, and a preferred range is from to 200 carbon atoms. My preferred dispersant compounds are in general the lower ethyleneamine derivatives of such 4-formylphthalic anhydride telomers of polyolefins.

Suitable lubricant base stocks for use with the additives of my invention are such as the mineral lubricating oils, synthetic hydrocarbon lubricating oils, synthetic lubricating oils of the polyalkylene oxide type, for example the Ucon oils marketed by Carbide and Carbon Corporation, as well as polycarboxylic acid ester type syn thetic lubricating oils, such as the esters of adipic acid, sebacic acid, azelaic acid, etc. While the additives of the present invention can be used alone in the base oil, they can also be used in combination with minor amounts, for example 0.02 weight percent to 10 weight percent, based upon the lubricant oil, of other lubricant addition agents, such as zinc dialkyl dithiophosphates, sulfurized terpenes, e.g. sulfurized dipentene, viscosity index improvers, pour point depressors, rust inhibitors, extreme pressure additives, etc.

One mode of preparation of the compounds of my invention is a telomerization reaction carried out with peroxide-type polymerization initiators under such conditions of temperature and pressure as to maintain a liquid phase in the reaction vessel. The product of such reaction will, of course, not have one precise alkyl chain length substituted in the 4-formyl-phthalic anhydride molecule; it will be a mixture of compounds having alkyl substituents near the average alkyl chain length in size.

Effective polymerization initiators are materials such as di-tertiary butyl peroxide, benzoyl peroxide, acetyl peroxide, various hydroperoxides, azo-bisisobutyronitrile, etc.

The temperature for the telomerization reaction must be high enough to generate sufficient free-radicals from the polymerization initiator to start the reaction: the pressure should be sufficient to maintain a liquid phase in the reaction vessel. The selection of the proper combination of initiators, temperature and pressure for most eifective reaction can be readily determined through simple experimentation by the ordinary worker in this art in light of my disclosure. A specific preparation of a compound within the scope of my invention was performed as follows:

To a 250 ml. Magne-Dash reactor there was charged 100 cc. of benzene as solvent, 5.0 g. of 4-formyl-phthalic anhydride and 2.0 cc. of di-tertiary butyl peroxide, as initiator. The reactor was closed, flushed with argon, and ethylene. The reactor and contents were brought to a temperature of 150 C., at which time ethylene was added to 1120 p.s.i.g. Polymerization was carried out for about 2.5 hours at 1000 to 1140 p.s.i.g. of ethylene. An additional 3.0 cc. of the peroxide was then added and the pressure was maintained at 940 to 1140 p.s.i.g. for about 6.5 hours. The total product of the reaction was recovered by removing the benzene solvent at room temperature under a vacuum of less than 1 mm. Hg.

The total reaction product was extracted with acetone at room temperature to provide an acetone-insoluble material, designated Fraction A, amounting to 16.5 g., and an acetone-soluble material, designate-d Fraction B, amounting to 10.5 g.

Fraction A, the higher molecular weight fraction, contained an alkanoyl group of about 254 carbon atoms in length, as calculated from the acid number.

Fraction B was subjected to analysis for saponification number and molecular weight, following drying in a vacuum oven at C. to remove about 2 g. of byproduct phthalic anhydride which resulted from decarbonylation during the polymerization reaction.

The molecular weight of Fraction B was found to be about 578, corresponding to addition of about 14 ethylene groups to the 4-formyl-phthalic anhydride starting material. The saponification number indicated addition of about 19 ethylene groups. Hence, Fraction B was a 4-alkanoyl-phthalic anhydride wherein the alkanoyl group contained about 34 carbon atoms.

In similar fashion, propylene, l-butene, isobutylene, 1- pentene, mixtures thereof, and the like, can be used in the preparation of telomerization products with 4-formylphthalic anhydride. The length of the alkyl group substituted into the 4-formyl-phthalic anhydride molecule can be readily varied by adjusting the proportions of the reactants, as will be evident to those skilled in this art.

A 5.5 g. sample of Fraction B was dissolved in 50 cc. of benzene and to this solution was added 2.9 g. of tetraethylene pentamine in 50 cc. of benzene. The resulting mixture was heated to boiling and the benzene solvent was removed by vaporization. The solid residue was dried in a vacuum oven at 80 C. overnight and about 8.4 g. of the tetraethylene pentamine derivative of 4-alkanoyl-phthalic anhydride was obtained.

The alkyleneamine derivatives of 4-alkanoyl-phthalic anhydrides made according to the above procedure may be di-amide compounds of the general formula:

wherein R is an alkyl group, R is an alkylene group and x is an integer depending upon the particular alkyleneamine chosen, suitably from 1 to 20.

The ethyleneamine derivative made as described hereinabove was subjected to a qualitative test for dispersancy as follows:

Into a 4-ounce tall form vial there was placed about 0.375 g. of the derivative. This was dissolved in a mixture of 25 g. benzene and 50 g. petroleum naphtha. To the solution there was added 4 g. of a carbon black-white oil suspension. The mixture was stirred thoroughly and allowed to stand undisturbed for 48 hours. A blank was prepared as above, except for omission of the ethyleneamine derivative, and allowed similarly to stand for 48 hours. At the end of the test period, the carbon suspended in the blank sample had settled out of suspension; that in the test sample remained in suspension.

The ethyleneamine compounds suitable for preparation of the ethyleneamine-4-formyl-phthalic anhydride derivatives of my invention are those of the general formula H N(R NH) H wherein x is at least 1 and R is an alkylene group, preferably ethylene. The upper limit for the value of x is dependent upon the degree of solubility desirable for a particular derivative. A practical upper limit is about 20 when R is ethylene; that is, about 40 carbon atoms. Suitable alkyleneamines are such compounds as ethylene diamine, diethylene triamine, triethylene tetraamine, pentaethylene hexamine, etc. Suitable compounds are also such as the homologues of the ethyleneamines, e.g. propylene amines, etc. Further, monoamines can be employed for preparation of the 4-alkanoyl-phthalic anhydride derivatives, suitable monoamines being such as ethylamine, propylamine, butylamine, and, in general, alkylamines containing from about 1 to about 40 carbon atoms.

Although the present .invention has been described with reference to specific embodiments thereof, variations within its scope will be apparent to those of ordinary skill in this art.

Having thus described my invention, what I claim is:

1. As new compositions of matter, organic compounds of the structure:

II C wherein R is an alkyl group containing at least 4 to about 1000 carbon atoms.

2. As new compositions of matter, the 4-formylphthalic anhydride telomers of an aliphatic polyolefin hydrocarbon which contains from about 4 to about 1000 carbon atoms in the polyolefin chain.

3. The compositions of claim 2 wherein the is polyethylene.

4. The compositions of claim 2 wherein the polyolefin is polypropylene.

5. The compositions of claim 2 wherein the polyolefin is polyisobutylene.

6. The method of preparing 4-alkanoyl-phthalic anhydride wherein the alkanoyl group contains from about 5 to about 1000 carbon atoms which comprises reacting a lower l-alkene with 4-formyl-phthalic anhydride, said reaction being initiated by a free-radical polymerization initiator.

7. As a new composition of matter, the reaction product made by reacting an organic compound of the structure:

polyolefin wherein R is an alkyl group containing at least 4 to about 1000 carbon atoms with an amine of the structure: H(NHR) NH wherein R is a lower alkylene group and 6 x is an integer of from 1 to 20, said reacting being accomplished by heating a mixture of said organic compound and said amine to boiling.

8. The composition of claim 7 wherein R contains from about 4 to about 1000 carbon atoms, R is ethylene and x is from 1 to 10.

9. The composition of claim 7 wherein R is polyethylene, R is an ethylene group and xis 4.

10. A lubricant composition comprising a major proportion of a normally liquid lubricant oil base stock and a minor amount suflicient to impart dispersancy up to about 30 percent by weight of a dispersant, wherein said dispersant is the reaction product made by reacting an organic compound of the structure:

H(NHR) NH wherein R is a lower alkylene group and x is an integer of from 1 to 20, said reacting being accomplished by heating a mixture of said 4-alkanoy1-phthalic anhydride and said alkylene amine to boiling.

References Cited by the Examiner UNITED STATES PATENTS 2,809,160 10/1957 Stewart et a1 252-51.5 X 2,810,696 10/1957 Lowe et al 252-51.5 X 2,971,027 2/1961 Hotten 2525l.5 X 3,090,753 5/1963 Matuszak 2.52396 X DANIEL E. WYMAN, Primary Examiner.

P. P. GARVIN, Assistant Examiner. 

10. A LUBRICANT COMPOSITION COMPRISING A MAJOR PROPORTION OF A NORMALLY LIQUID LUBRICANT OIL BASE STOCK AND A MINOR AMOUNT SUFFICIENT TO IMPART DISPERSANCY UP TO ABOUT 30 PERCENT BY WEIGHT OF A DISPERSANT, WHEREIN SAID DISPERSANT IS THE REACTION PRODUCT MADE BY REATING AN ORGANIC COMPOUND OF THE STRUCTURE: 